Civil Engineering Reference
In-Depth Information
address the need for Member States to accept new pozzolans, affording the
industries concerned greater flexibility as they rise to the challenges facing
21st-century society.
For this reason, recent research has focused on the identification of new
wastes whose characteristics make it apt for use as a supplementary cementitious
material in future blended cements. This line of endeavour is one of the
cement industry's research priorities and worldwide environmental policy
guidelines, which stress the need to recycle rather than stockpile industrial
waste. It also forms part of the European Commission premises on waste
co-processing in the cement industry as a key element in combating climate
change and reducing greenhouse gas emissions between 80 and 90% by
2050, in keeping with Community targets (Infocemento, 2011 Isrcer, 2011;
Oficemen, 2011).
As a result of the foregoing and in light of the present global economic
crisis, the urgent need to find alternative materials is a worldwide priority,
given the substantial losses incurred by the construction industry, mainly
in Spain. That, however, calls for a firm commitment by all concerned:
waste-generating companies, research institutions, the cement and concrete
industry and government at all levels.
This chapter discusses the main scientific-technical features of the alternative
industrial wastes and by-products studied by the 'Materials Recycling'
research team at the Eduardo Torroja Institute (Spanish National Research
Council), which may serve as alternative artificial pozzolans in the future.
For a clearer understanding of the findings, industial wastes have been
divided into two main groups: artificial pozzolans from industrial processes
(SiMn slag, Cu slag, coal combustion bottom ash, fluid catalytic cracking)
and artificial pozzolans from agro-industrial waste (sugar cane, paper sludge,
rice husks, bamboo leaves).
5.2 Sources and availability
5.2.1 Artificial pozzolans generated in industrial
processes
Silicon-manganese slag (SiMn)
This kind of pozzolan is obtained during SiMn production as a combination
of the non-profitable part of the raw materials and the fluxes such as quartz
or lime that are added to the ore in ferroalloy production furnaces to endow
the cast-iron products with certain physical properties. Due to the difference
in density, this slag can be separated from the ferroalloy (SiMn) during
casting and poured onto a slag bed, from where it is transported, classified
and stored, if necessary.
Slag generation the world over comes to around 10 Mt per year, 2.2 Mt
